The aims of this application are to: (1) evaluate gender differences in antiretroviral treatment outcome;and (2) if gender differences are detected, examine factors associated with these differences. Specific Aim 1 will be accomplished by testing a set of hypotheses that women differ from men on the following measures of response to first-line antiretroviral therapy (ART) including: (a) all-cause and HIV-related mortality in the first 24 months after initiating therapy;(b) immunologic response, as measured by change in CD4+ cell count in the first 24 months;(c) virologic response as measured by the proportion of patients who reached the undetectable level of viral load in the first 24 months;(d) ART-related side effects associated with different regimens, including symptoms and laboratory-based diagnoses within the first 24 months;and (e) time to stopping first- line ART after initiating therapy. Specific Aim 2 will be accomplished by performing multivariable analysis for any outcome found to differ significantly between women and men. Covariates that might explain the treatment outcome differences will be examined to determine if they differ in proportion between women and men. Those that do will be inserted into the multivariate model to determine if any are statistically significant. All analyses will be conducted using a national ART Database established by the China Center for Disease Control and Promotion (China CDC). This large database collects demographic and clinical care information on all patients participating in the free-ART program, which provides a unique resource for examining gender- related differences in community-based HIV treatment outcomes. Determining whether these differences exist and understanding their causes will benefit HIV-infected individuals not only in China but perhaps throughout the developing world. PUBLIC HEALTH RELEVANCE: China has successfully implemented an antiretroviral treatment (ART) program, but many challenges remain in managing the program. The proposed study is a secondary data analysis of the China National Antiretroviral Treatment Database. The findings from the proposed analysis will provide invaluable information on the understanding of treatment differences between HIV-infected women and men in community-based ART programs and will assure the future success of the ART program in China. The analysis may also provide much-needed information to guide the assessment of other community-based HIV treatment programs in developing countries.